I would add another lesson:

The machine is not the cloud.

For instance I never thought of any EC2 instance as itself being really worth anything as a server in terms of spending any amount of time trying to get one particular one running correctly.

Instead, I've mostly thought of EC2 as a rotating pool of flimsy things that resemble machines that all together have the possibility of being something much greater.

So to me in reading (well, skimming) this article (which is a pretty good article) a lot of time could've been saved IMHO of forgetting about any software designed for single machines, or perhaps more specifically, designed for optimization that only things of a single machine's performance.